To the Editor.—Subsalicylate bismuth (Pepto-Bismol) has been shown to be effective for the prevention of traveler's diarrhea (emporiatic enteritis) (1980;243:237).1 Because of the large volume of medication required (60 mL four times a day), travelers may be tempted to substitute Pepto-Bismol tablets. I would like to point out a potential risk of this substitution.Pepto-Bismol tablets each contain 300 mg of subsalicylate bismuth, and, unlike the liquid, 350 mg of calcium carbonate. This fact is not mentioned on the package or in the Physicians' Desk Reference. A traveler taking the equivalent of the recommended daily dose of 240 mL (4,200 mg of subsalicylate bismuth) would ingest 14 tablets per day. This corresponds to a load of 4.9 g of calcium carbonate per day. While most normal persons are able to excrete this calcium load, some individuals will be susceptible to hypercalcemia through the milk-alkali syndrome. The amount of